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Science Final 8th
Ashie's Science Final
Term | Definition |
---|---|
Matter | made up of extremely small particles that make up atoms & molecules that are always in motion. |
All matter | has energy. |
Matter | anything that has mass & volume. |
meter | SI unit for measuring length |
grams (or kilograms) | SI Unit for measuring mass |
liters | SI Unit for measuring volume |
Scientific method | set of steps scientists use to answer questions and solve problems. |
Densest liquids | settle to the bottom of a container |
Least dense liquids | float on top of container |
Density of water | One |
Chemical changes | the composition of matter changes. |
Physical changes | do not change the composition of matter. |
Crystalline solids | have particles in repeating patterns of rows |
Amorphous solids | have an irregular pattern of particles. |
Three properties of Gases | Have particles that are 1) very fast moving 2) spread far apart 3) have no definite shape or volume. |
Evaporation | liquid becomes a gas. E.g. Puddle of water becoming water vapor |
Condensation | gas to a liquid. E.g. water drops on a cold glass |
Compound | Two or more elements join together chemically to form a new substance. |
Two examples of chemical properties | 1) flammability and 2) reactivity to oxygen or acid. |
Soluble | Substance can be dissolved in water. |
Solutions | Formed when two or more substances are evenly mixed. |
Speed is determined by what two factors | distance and time. |
Velocity is determined by what 3 factors | 1) distance 2) time and 3) direction. |
Balanced forces | Have a net force of Zero Newtons. |
Gravitational force | Determined by mass and distance. |
The greater the mass | the greater the gravity (e.g. sun [large] vs moon [small]). |
The closer the distance | the stronger the gravity (e.g. sun's pull on Earth vs Pluto). |
The Law of Conservation of momentum | states that when objects collide the total amount of momentum stays the same. |
(In the absence of air resistance) why do all objects fall to the ground at the same rate | Because the acceleration due to gravity is the same for all objects on earth. |
Newton’s 1st law of motion (law of inertia) | an object at rest will remain at rest / an object in motion will remain in motion at a constant speed and in a straight line unless acted on by an unbalanced force. |
Atom | The smallest particle which an element can be divided and still be the same substance. |
Nucleus of an atom is | dense & positively charged. |
Electrons are where? | In the electron cloud. |
Isotopes | Atoms that have the same number of protons but a different number of neutrons. |
groups or families | Vertical columns on the periodic table |
periods | horizontal rows on the periodic table |
Metals | Elements to the left of the zigzag line of the periodic table. |
Nonmetals | Elements to the right of the zigzag line of the periodic table (these make up the majority of the elements in the periodic table). |
Metalloids | Elements that scatter either side of the zigzag line of the periodic table |
Mendeleev | Arranged the elements by increasing atomic mass |
Henry Mosley | Arranged the current periodic table by increasing atomic number. |
How can you tell a chemical change has occurred | a new substance with different properties from the original substances is formed. |
Reactants | are before the arrow in a chemical equation |
Products | are after the arrow in a chemical equation. |
The Law of Conservation of Mass | Mass cannot be created nor destroyed in a chemical reaction. |
When counting atoms | if no subscript is written it is assumed to be one atom. |
Acids | 1) have a sour taste & 2) turn blue litmus paper red. |
Bases | 1) have a bitter taste 2) feel slippery & 3) turn litmus paper blue. |
pH above 7 | bases. |
pH equals 7 | neutral |
pH below 7 | acids |
Why are telescopes put in space | to avoid interference from Earth’s atmosphere. |
One rotation of Earth happens | Every 24 hours. |
365 ¼ days (1 year) | One revolution (orbit) of Earth around the sun |
29 ½ days (1 month) | One orbit of moon around the Earth |
Color of a star depends on | its temperature. |
Phases of the moon are caused by | the relative positions of the moon Earth and the sun. |
Total solar eclipse | when the shadow of the moon falls on the Earth. |
How did the moon form | A large planet sized body struck the Earth - called the Collision Ring Theory. |
Why do we only see one side of the moon (the near side) | The moon’s period of rotation is equal to its period of revolution |